Polymerization catalysts, preparation of polyolefins, organotransition metal compounds and ligands

ABSTRACT

The present invention relates to catalyst systems which can be used for preparing homopolymers or copolymers of olefins and are obtainable by reacting at least one transition metal compound with at least one cocatalyst which is able to convert the transition metal compound into a species which displays polymerization activity toward at least one olefin, wherein the transition metal compound has the formula (I), where M is an element of group 3, 4, 5, 6, 7, 8, 9 or 10 of the Periodic Table of the Elements or the lanthanides, X are identical or different and are each an organic or inorganic anionic monovalent ligand, where two radicals X may also be joined to form a divalent radical, n is 1, 2 , 3 or 4, L 1  is an organic or inorganic uncharged ligand, h is an integer from 0 to 4, R 1  and R 1′  can be identical or different and are each hydrogen or an organic radical having from 1 to 40 carbon atoms, R 2  and R 2′  can be identical or different and are each a substituted or unsubstituted C 6 -C 40 -aryl radical or C 2 -C 40 -heteroaromatic radical containing at least one heteroatom selected from the group consisting of O, N, S or P, and Y is a divalent group between the two sp 2 -hybridized carbon atoms and is selected from the group consisting of the two-membered bridges —N(R 3 )—N(R 4 )— and —O—N(R 5 ) and the one-membered bridges —O—, —N(R 6 )—, —N(OR 7 )— and —N(NR 8 R 9 )—, where R 3 , R 4 , R 5 , R 6 , R 7 , R 8  and R 9  are identical or different and are each hydrogen or an organic radical having from 1 to 40 carbon atoms, where two adjacent radicals may also form a divalent organic group having from 1 to 40 carbon atoms which together with the atom or atoms connecting its ends forms a heterocyclic ring system, to the use of such catalyst systems for preparing polyolefins, to a process for preparing polyolefins by polymerization or copolymerization of at least one olefin in the presence of a catalyst system according to the present invention, to transition metal compounds of the formula (I) themselves, to the use of diimine ligand systems for preparing transition metal compounds and to the preparation of transition metal compounds and specific diimine ligand systems themselves.

The present invention relates to catalyst systems which can be used forpreparing homopolymers or copolymers of olefins and are obtainable byreacting at least one transition metal compound with at least onecocatalyst which is able to convert the transition metal compound into aspecies which displays polymerization activity toward at least oneolefin, wherein the transition metal compound has the formula (I),

where

-   M is an element of group 3, 4, 5, 6, 7, 8, 9 or 10 of the Periodic    Table of the Elements or the lanthanides,-   X are identical or different and are each an organic or inorganic    anionic monovalent ligand, where two radicals X may also be joined    to form a divalent radical,-   n is 1, 2, 3 or 4,-   L¹ is an organic or inorganic uncharged ligand,-   h is an integer from 0 to 4,-   R¹ and R^(1′) can be identical or different and are each hydrogen or    an organic radical having from 1 to 40 carbon atoms,-   R² and R^(2′) can be identical or different and are each a    substituted or unsubstituted C₆-C₄₀-aryl radical or    C₂-C₄₀-heteroaromatic radical containing at least one heteroatom    selected from the group consisting of O, N, S or P, and-   Y is a divalent group between the two sp²-hybridized carbon atoms    and is selected from the group consisting of the two-membered    bridges —N(R³)—N(R⁴)— and —O—N(R⁵)— and the one-membered bridges    —O—,    —N(R⁶)—, —N(OR⁷)— and —N(NR⁸R⁹)—,    where    -   R³, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ are identical or different and are        each hydrogen or an organic radical having from 1 to 40 carbon        atoms, where two adjacent radicals may also form a divalent        organic group having from 1 to 40 carbon atoms which together        with the atom or atoms connecting its ends forms a heterocyclic        ring system.

In addition, the present invention relates to the use of such catalystsystems for preparing polyolefins, to a process for preparingpolyolefins by polymerization or copolymerization of at least one olefinin the presence of a catalyst system according to the present invention,to the transition metal compounds of the formula (I) themselves, to theuse of diimine ligand systems for preparing transition metal compoundsand to the preparation of transition metal compounds and specificdiimine ligand systems themselves.

Polymers and copolymers of olefins are of great economic importancebecause the monomers are readily available in large quantities andbecause the polymers can be varied within a wide range by variation ofthe production process or the processing parameters. In the productionprocess, particular attention has to be paid to the catalyst used. Apartfrom Ziegler-Natta catalysts, various single-site catalysts are ofincreasing importance. In these, central atoms which have been examinedin detail include both Zr as in, for example, metallocene catalysts(H.-H. Brintzinger et al., Angew. Chem. 1995, 107, 1255), and Ni or Pd(WO 96/23010) or Fe and Co (e.g. WO 98/27124). The complexes of Ni, Pd,Fe and Co are also referred to as complexes of “late transition metals”.

Metallocene catalysts have disadvantages in industrial use. The mostfrequently used metallocenes, i.e. zirconocenes and hafnocenes, aresensitive to hydrolysis. Furthermore, most metallocenes are sensitivetoward many catalyst poisons such as alcohols, ethers or carbonmonoxide, which makes careful purification of the monomers necessary.

While Ni or Pd complexes (WO 96/23010) catalyze the formation of highlybranched polymers which are of little commercial interest, the use of Feor Co complexes leads to the formation of highly linear polyethylenehaving very small proportions of comonomer.

As G. J. P. Britovsek et al. show in Angew. Chem. 1999, 111, 448 and inAngew. Chem. Int. Ed. Engl. 1999, 38, 428, the search for very versatilepolymerization-active complexes continues to be of importance because ofthe great commercial importance of polyolefins. There is interest infinding polymerization-active complexes which have a particularlyfavorable property profile from a process engineering point of view.

It is an object of the present invention to find novel catalyst systemsfor the polymerization of olefins which are based on nonmetallocenes, toprovide novel complexes which are suitable for the polymerization ofolefins to form high molecular weight polymers, to provide a process forpreparing the complexes of the present invention and to provide aneconomical process for the polymerization or copolymerization of olefinsusing the catalyst systems of the present invention.

We have found that this object is achieved by the catalyst systemsmentioned at the outset.

In formula I, the variables are defined as follows:

M is an element of group 3, 4, 5, 6, 7, 8, 9 or 10 of the Periodic Tableof the Elements or the lanthanides, for example scandium, yttrium,titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium,molybdenum, tungsten, manganese, iron, cobalt, nickel or palladium,preferably iron, nickel or palladium, particularly preferably nickel orpalladium, in particular nickel.

The radicals X can be identical or different, in particular identical,and are each an organic or inorganic anionic monovalent ligand, wheretwo radicals X may also be linked to form a divalent radical. X ispreferably halogen, for example fluorine, chlorine, bromine, iodine,preferably chlorine or bromine, hydrogen, C₁-C₂₀-, preferablyC₁-C₄-alkyl, C₂-C₂₀-, preferably C₂-C₄-alkenyl, C₆-C₂₂-, preferablyC₆-C₁₀-aryl, an alkylaryl or arylalkyl group having from 1 to 10,preferably from 1 to 4, carbon atoms in the alkyl part and from 6 to 22,preferably from 6 to 10, carbon atoms in the aryl part. X isparticularly preferably halogen.

n is 1, 2, 3 or 4, and usually corresponds to the oxidation number of M.Preference is given to n being 2 or 3, in particular 2.

L¹ is an organic or inorganic uncharged ligand. Examples of suchuncharged ligands are phosphines such as triphenylphosphine, amines suchas triethylamine or N,N,N′,N′-tetramethylethylenediamine, ethers such asdialkyl ethers, e.g. diethyl ether, or cyclic ethers, e.g.tetrahydrofuran, water, alcohols such as methanol or ethanol, pyridine,pyridine derivatives such as 2-picoline, 3-picoline, 4-picoline,2,3-lutidine, 2,4-lutidine, 2,5-lutidine, 2,6-lutidine or 3,5-lutidine,carbon monoxide and also C₁-C₁₂-alkylnitriles or C₆-C₁₄-arylnitrilessuch as acetonitrile, propionitrile, butyronitrile or benzonitrile.Furthermore, compounds having one or more ethylenically unsaturateddouble bonds can also serve as ligand.

h is an integer from 0 to 4.

R¹ and R^(1′) can be identical or different, preferably identical, andare each hydrogen or an organic radical having from 1 to 40 carbonatoms.

Preferred examples of such radicals are cyclic, branched or unbranchedC₁-C₂₀-, preferably C₁-C₈-alkyl radicals, C₂₋C₂₀-, preferablyC₂-C₈-alkenyl radicals, C₆-C₂₂-, preferably C₆-C₁₀-aryl radicals,alkylaryl or arylalkyl radicals having from 1 to 10, preferably from 1to 4, carbon atoms in the alkyl part and from 6 to 22, preferably from 6to 10, carbon atoms in the aryl part, where the radicals may also behalogenated, or the radicals may also be substituted or unsubstituted,saturated or unsaturated, in particular aromatic, heterocyclic radicalswhich have from 2 to 40, in particular from 4 to 20 carbon atoms andcontain at least one heteroatom, preferably selected from the groupconsisting of O, N, S and P, in particular N.

Particular preference is given to R¹ and R^(1′) each being hydrogen, acyclic, branched or unbranched C₁-C₈-alkyl radical, a C₆-C₁₀-arylradical, an alkylaryl or arylalkyl radical having from 1 to 4 carbonatoms in the alkyl part and from 6 to 10 carbon atoms in the aryl partor R¹ and R^(1′) being five- or six-membered nitrogen-containingheteroaromatics which are bound via a single bond and may be substitutedor unsubstituted.

Examples of particularly preferred radicals R¹ and R^(1′) are hydrogen,methyl, ethyl, n-propyl, iso-propyl, n-butyl, i-butyl, s-butyl, t-butyl,n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, benzyl,2-phenylethyl, phenyl, pentafluorophenyl, 2-tolyl, 3-tolyl, 4-tolyl,2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl,2,6-dimethylphenyl, 2,6-di(isopropyl)phenyl, 3,4-dimethylphenyl,3,5-dimethylphenyl, 3,5-di(tert-butyl)-phenyl, 2,4,6-trimethylphenyl,2,3,4-trimethylphenyl, 1-naphthyl, 2-naphthyl, phenanthryl,p-isopropylphenyl, p-tert-butylphenyl, p-s-butylphenyl,p-cyclohexylphenyl, p-trimethylsilylphenyl, N-pyrrolyl, pyrrol-2-yl,pyrrol-3-yl, N-imidazolyl, 2-imidazolyl, 4-imidazolyl,1,2,4-triazol-3-yl, 1,2,4-triazol-4-yl, 2-pyridyl, 3-pyridyl, 4-pyridyl,3-pyridazinyl, 4-pyridazinyl, 2-pyrimidinyl, 4-pyrimidinyl,5-pyrimidinyl, N-indolyl and N-carbazolyl; where the last-namednitrogen-containing heterocycles may also bear a substituent such asmethyl, ethyl, isopropyl, tert-butyl or phenyl.

Very particular preference is given to R¹ and R¹′ each being aC₆-C₁₀-aryl radical or an alkylaryl radical having from 1 to 4 carbonatoms in the alkyl part and from 6 to 10 carbon atoms in the aryl partor R¹ and R^(1′) being five- or six-membered nitrogen-containingheteroaromatics which are bound via a single bond and may be substitutedor unsubstituted. Especial preference is given to R¹ and R^(1′) eachbeing a 2,6-di-C₁-C₄-alkyl-substituted phenyl radical.

R² and R^(2′) can be identical or different, preferably identical, andare each a substituted or unsubstituted C₆-C₄₀-aryl radical or aC₂-C₄₀-heteroaromatic radical containing at least one heteroatqmselected from the group consisting of O, N, S and P, in particular N.

R² and R^(2′) are preferably each a substituted or unsubstituted arylradical such as phenyl, pentafluorophenyl, 2-tolyl, 3-tolyl, 4-tolyl,2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl,2,6-dimethylphenyl, 2,6-di(isopropyl)phenyl, 3,4-dimethylphenyl,3,5-dimethylphenyl, 3,5-di(tert-butyl)phenyl, 2,4,6-trimethylphenyl,2,3,4-trimethylphenyl, 1-naphthyl, 2-naphthyl, phenanthryl,p-isopropylphenyl, p-tert-butylphenyl, p-s-butylphenyl,p-cyclohexylphenyl or p-trimethylsilylphenyl.

Y is a divalent group which is located between the sp²-hybridized carbonatoms and is selected from the group consisting of the two-memberedbridges —N(R³)—N(R⁴)— and —O—N(R⁵)— and the one-membered bridges-O—,—N(R⁶)—, —N(OR⁷)— and —N(NR⁸R⁹)—, preferably the two-membered bridgesN(R³)—N(R⁴)— and —O—N(R⁵)—, where

R³, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ are identical or different and are eachhydrogen or an organic radical having from 1 to 40 carbon atoms, wheretwo adjacent radicals may also form a divalent organic group which hasfrom 1 to 40 carbon atoms and together with the atom or atoms connectingits ends forms a heterocyclic ring system.

Preferred examples of the radicals R³, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ arecyclic, branched or un-branched C₁-C₂₀-, preferably C₁-C₈-alkylradicals, C₂-C₂₀-, preferably C₂-C₈-alkenyl radicals, C₆-C₂₂-,preferably C₆-C₁₀-aryl radicals, alkylaryl or arylalkyl radicals havingfrom 1 to 10, preferably from 1 to 4, carbon atoms in the alkyl part andfrom 6 to 22, preferably from 6 to 10, carbon atoms in the aryl part,where the radicals may also be halogenated, or the radicals may besubstituted or unsubstituted, saturated or unsaturated, in particulararomatic, heterocyclic radicals which have from 2 to 40, in particularfrom 4 to 20, carbon atoms and contain at least one heteroatom,preferably selected from the group consisting of O, N, S and P, inparticular N.

If two adjacent radicals together with the atom or atoms connecting themform a heterocyclic ring system, this is preferably a 4- to 8-membered,in particular 5- or 6-membered, ring system which may be saturated orunsaturated.

According to the present invention, the radicals R¹, R^(1′), R², R^(2′),R³, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ can also contain functional groups withoutaltering the polymerization properties of the catalyst system of thepresent invention, as long as these functional groups are chemicallyinert under the polymerization conditions.

Furthermore, the substituents according to the present invention are,unless restricted further, defined as follows:

The term “organic radical having from 1 to 40 carbon atoms” as used inthe present text refers, for example, to C₁-C₄₀-alkyl radicals,C₁-C₁₀-fluoroalkyl radicals, C₁-C₁₂-alkoxy radicals, saturatedC₃-C₂₀-heterocyclic radicals, C₆-C₄₀-aryl radicals,C₂-C₄₀-heteroaromatic radicals, C₆-C₁₀-fluoroaryl radicals,C₆-C₁₀-aryloxy radicals, C₃-C₁₈-trialkylsilyl radicals, C₂-C₂₀-alkenylradicals, C₂-C₂₀-alkynyl radicals, C₇-C₄₀-arylalkyl radicals orC₈-C₄₀-arylalkenyl radicals.

The term “alkyl” as used in the present text encompasses linear orsingly branched or multiply branched saturated hydrocarbons which mayalso be cyclic. Preference is given to a C₁-C₁₈-alkyl, such as methyl,ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl,n-decyl, cyclopentyl or cyclohexyl, isopropyl, isobutyl, isopentyl,isohexyl, sec-butyl or tert-butyl.

The term “alkenyl” as used in the present text encompasses linear orsingly branched or multiply branched hydrocarbons having one or more C—Cdouble bonds which may be cumulated or alternating.

The term “saturated heterocyclic radical” as used in the present textrefers, for example, to monocyclic or polycyclic, substituted orunsubstituted hydrocarbon radicals in which one or more carbon atoms, CHgroups and/or CH₂ groups are replaced by heteroatoms which arepreferably selected from the group consisting of O, S, N and P.Preferred examples of substituted or unsubstituted, saturatedheterocyclic radicals are pyrrolidinyl, imidazolidinyl, pyrazolidinyl,piperidyl, piperazinyl, morpholinyl, tetrahydrofuranyl,tetrahydropyranyl, tetrahydrothienyl and the like, and also methyl-,ethyl-, propyl-, isopropyl- and tert-butyl-substituted derivativesthereof.

The term “aryl” as used in the present text refers, for example, toaromatic and fused or unfused polyaromatic hydrocarbon substituentswhich may be monosubstituted or polysubstituted by linear or branchedC₁-C₁₈-alkyl, C₁-C₁₈-alkoxy, C₂-C₁₀-alkenyl or halogen, in particularfluorine. Preferred examples of substituted and unsubstituted arylradicals are, in particular, phenyl, pentafluorophenyl, 4-methylphenyl,4-ethylphenyl, 4-propylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl,4-methoxyphenyl, 1-naphthyl, 9-anthryl, 9-phenanthryl,3,5-dimethylphenyl, 3,5-di-tert-butylphenyl or 4-trifluoromethylphenyl.

The term “heteroaromatic radical” as used in the present text refers,for example, to aromatic hydrocarbon substituents in which one or morecarbon atoms are replaced by nitrogen, phosphorus, oxygen or sulfuratoms or combinations thereof. These may, like the aryl radicals, bemonosubstituted or polysubstituted by linear or branched C₁-C₁₈-alkyl,C₂-C₁₀-alkenyl or halogen, in particular fluorine. Preferred examplesare furyl, thienyl, pyrrolyl, pyridyl, pyrazolyl, imidazolyl, oxazolyl;thiazolyl, pyrimidinyl, pyrazinyl and the like, and also methyl-,ethyl-, propyl-, isopropyl- and tert-butyl-substituted derivativesthereof.

The term “arylalkyl” as used in the present text refers, for example, toaryl-containing substituents whose aryl radical is linked via an alkylchain to the remainder of the molecule. Preferred examples are benzyl,substituted benzyl, phenethyl, substituted phenethyl and the like.

The terms fluoroalkyl and fluoroaryl mean that at least one, preferablymore than one, and at most all hydrogen atoms of the respectivesubstituent are replaced by fluorine atoms. Examples offluorine-containing substituents which are preferred according to thepresent invention are trifluoromethyl, 2,2,2-trifluoroethyl,pentafluorophenyl, 4-trifluoromethylphenyl, 4-perfluoro-tert-butylphenyland the like.

Preference is given to catalyst systems as described above in which thetransition metal compound has a formula (I) in which

-   M is Ni or Pd, in particular Ni,-   X is halogen, for example fluorine, chlorine, bromine or iodine,    preferably chlorine or bromine, in particular bromine,-   n is 2,-   h is 0,-   R¹ and R^(1′) are identical and are each a substituted or    unsubstituted C₆-C₄₀-aryl radical or a nitrogen-containing    heteroaromatic radical having from 4 to 20 carbon atoms, preferably    a substituted or unsubstituted C₆-C₄₀ aryl radical or an alkylaryl    radical having from 1 to 10, preferably from 1 to 4, carbon atoms in    the alkyl part and from 6 to 22, preferably from 6 to 10, carbon    atoms in the aryl part, in particular a phenyl radical substituted    by two C₁-C₄-alkyl radicals in positions 2 and 6, where the radicals    may also be halogenated and preferred examples are phenyl,    pentafluorophenyl, 2-tolyl, 3-tolyl, 4-tolyl, 2,3-dimethylphenyl,    2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl,    2,6-di(isopropyl)phenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl,    3,5-di(tert-butyl)phenyl, 2,4,6-trimethylphenyl,    2,3,4-trimethylphenyl, 1-naphthyl, 2-naphthyl, phenanthryl,    p-isopropylphenyl, p-tert-butylphenyl, p-s-butylphenyl,    p-cyclohexylphenyl and p-trimethylsilylphenyl, in particular    2,6-dimethylphenyl and 2,6-di(isopropyl)phenyl,    and    the other variables are as defined for the formula (I).

Illustrative but nonlimiting examples of transition metal compounds ofthe formula (I) which can be used as constituents of catalyst systems ofthe present invention are:

The synthesis of the complexes is known in principle and can be carriedout as described in EP 1336615.

The cocatalyst which together with the above-described transition metalcompound of the formula (I) forms the polymerization-active catalystsystem of the present invention is able to convert the transition metalcompound into a species which displays polymerization activity toward atleast one olefin. The cocatalyst is therefore sometimes also referred toas activating compound. The polymerization-active transition metalspecies is frequently a cationic species. In this case, the cocatalystis frequently also referred to as cation-forming compound.

Suitable catalysts or cation-forming compounds are, for example,aluminoxanes, strong uncharged Lewis acids, ionic compounds having aLewis-acid cation or ionic compounds containing a Brönsted acid ascation. Preference is given to an aluminoxane as cocatalyst.

Aluminoxanes which can be used are, for example, the compounds describedin WO 00/31090. Particularly useful compounds are open-chain or cyclicaluminoxane compounds of the formulae (III) or (IV)

where

-   R¹⁰ is a C₁-C₄-alkyl group, preferably a methyl or ethyl group, and    m is an integer from 5 to 30, preferably from 10 to 25.

These oligomeric aluminoxane compounds are usually prepared by reactinga solution of trialkylaluminum with water. In general, the oligomericaluminoxane compounds obtained in this way are in the form of mixturesof both linear and cyclic chain molecules of various lengths, so that mis to be regarded as a mean. The aluminoxane compounds can also bepresent in a mixture with other metal alkyls, preferably aluminumalkyls.

Furthermore, modified aluminoxanes in which some of the hydrocarbonradicals or hydrogen atoms have been replaced by alkoxy, aryloxy, siloxyor amide groups can also be used in place of the aluminoxane compoundsof the formulae (III) or (IV).

It has been found to be advantageous to use the transition metalcompound and the aluminoxane compounds in such amounts that the atomicratio of aluminum from the aluminoxane compounds to the transition metalfrom the transition metal compound is in the range from 10:1 to 1000:1,preferably in the range from 20:1 to 500:1 and in particular in therange from 30:1 to 400:1.

As strong, uncharged Lewis acids, preference is given to compounds ofthe formula (V)M¹X¹X²X³  (V).where

-   M¹ is an element of group 13 of the Periodic Table of the Elements,    in particular B, Al or Ga, preferably B,-   X¹, X² and X³ are each, independently of one another, hydrogen,    C₁-C₁₀-alkyl, C₆-C₁₅aryl, alkylaryl, arylalkyl, haloalkyl or    haloaryl each having from 1 to 10 carbon atoms in the alkyl radical    and from 6 to 20 carbon atoms in the aryl radical or fluorine,    chlorine, bromine or iodine, in particular haloaryl, preferably    pentafluorophenyl.

Further examples of strong, uncharged Lewis acids are given in WO00/31090.

Particular preference is given to compounds of the formula (V) in whichX¹, X² and X³ are identical, preferably tris(pentafluorophenyl)borane.

Strong uncharged Lewis acids which are suitable as cocatalyst orcation-forming compounds also include the reaction products from thereaction of a boronic acid with two equivalents of a trialkylaluminum orthe reaction products from the reaction of a trialkylaluminum with twoequivalents of an acidic fluorinated, in particular perfluorinated,carbon compound such as pentafluorophenol orbis(pentafluorophenyl)borinic acid.

Suitable ionic compounds having Lewis-acid cations include salt-likecompounds of the cation of the formula (VI)[(Z^(a+))Q¹Q² . . . Q^(z)]^(d+)  (VI)where

-   Z is an element of groups 1 to 16 of the Periodic Table of the    Elements,-   Q¹ to Q^(z) are singly negatively charged groups such as    C₁-C₂₈-alkyl, C₆-C₁₅-aryl, alkylaryl, arylalkyl, haloalkyl, haloaryl    each having from 6 to 20 carbon atoms in the aryl radical and from 1    to 28 carbon atoms in the alkyl radical, C₃-C₁₀-cycloalkyl, which    may bear C₁-C₁₀-alkyl groups as substituents, halogen,    C₁-C₂₈-alkoxy, C₆-C₁₅-aryloxy, silyl or mercaptyl groups,-   a is an integer from 1 to 6 and-   z is an integer from 0 to 5, and-   d is the difference a−z, but d is greater than or equal to 1.

Particularly useful cations are carbonium cations, oxonium cations andsulfonium cations and also cationic transition metal complexes.Particular mention may be made of the triphenylmethyl cation, the silvercation and the 1,1′-dimethylferrocenyl cation. They preferably havenoncoordinating counterions, in particular boron compounds as are alsomentioned in WO 91/09882, preferably tetrakis(pentafluorophenyl)borate.

Salts having noncoordinating anions can also be prepared by adding aboron or aluminum compound, e.g. an aluminum alkyl, to a second compoundwhich can react to link two or more boron or aluminum atoms, e.g. water,and a third compound which forms an ionizing ionic compound with theboron or aluminum compound, e.g. triphenylchloromethane. A fourthcompound which likewise reacts with the boron or aluminum compound, e.g.pentafluorophenol, can additionally be added.

Ionic compounds containing Brönsted acids as cations preferably likewisehave noncoordinating counterions. As Brönsted acids, particularpreference is given to protonated amine or aniline derivatives.Preferred cations are N,N-dimethylanilinium,N,N-dimethylcylohexylammonium and N,N-dimethylbenzylammonium and alsoderivatives of the latter two.

Preferred ionic compounds as cocatalysts or cation-forming compoundsare, in particular, N,N-di-methylaniliniumtetrakis(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium.tetrakis(pentafluorophenyl)borate and N,N-dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate.

It is also possible for two or more borate anions to be joined to oneanother, as in the dianion [(C₆F₅)₂B—C₆F₄—B(C₆F₅)₂]²⁻, or the borateanion can be bound via a bridge having a suitable functional group tothe surface of a support particle.

Further suitable cocatalysts or cation-forming compounds are listed inWO 00/31090.

The amount of strong, uncharged Lewis acids, ionic compounds havingLewis-acid cations or ionic compounds containing Brönsted acids ascations is usually from 0.1 to 20 equivalents, preferably from 1 to 10equivalents, based on the transition metal compound.

Suitable cocatalysts or cation-forming compounds also includeboron-aluminum compounds such asdi[bis(pentafluorophenylboroxy)]methylalane. Such boron-aluminumcompounds are disclosed, for example, in WO 99/06414.

It is also possible to use mixtures of all of the abovementionedcocatalysts or cation-forming compounds. Preferred mixtures comprisealuminoxanes, in particular methylaluminoxane, and an ionic compound, inparticular one containing the tetrakis(pentafluorophenyl)borate anion,and/or a strong uncharged Lewis acid, in particulartris(pentafluorophenyl)borane.

Preference is given to using both the transition metal compound and thecocatalysts or cation forming compounds in a solvent, with aromatichydrocarbons having from 6 to 20 carbon atoms, in particular xylenes andtoluene, being preferred.

The catalyst system of the present invention can further comprise ametal compound of the formula (VII),M²(R¹¹)_(r)(R¹²)_(s)(R¹³)_(t)  (VII)where

-   M² is an alkali metal, an alkaline earth metal or a metal of group    13 of the Periodic Table of the Elements, i.e. boron, aluminum,    gallium, indium or thallium,-   R¹¹ is hydrogen, C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl or arylalkyl    each having from 1 to 10 carbon atoms in the alkyl part and from 6    to 20 carbon atoms in the aryl part,-   R¹² and R¹³ are identical or different and are each hydrogen,    halogen, C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl, arylalkyl or alkoxy    each having from 1 to 10 carbon atoms in the alkyl radical and from    6 to 20 carbon atoms in the aryl radical,-   r is an integer from 1 to 3,    and-   s and t are integers from 0 to 2, where the sum r+s+t corresponds to    the valence of M²,    where the metal compound of the formula (VII) is usually not    identical to the cocatalyst or the cation-forming compound. It is    also possible to use mixtures of various metal compounds of the    formula (VII).

Among the metal compounds of the formula (VII), preference is given tothose in which

-   M² is lithium, magnesium or aluminum and-   R¹² and R¹³ are each C₁-C₁₀-alkyl.

Particularly preferred metal compounds of the formula (VII) aren-butyllithium, n-butyl-n-octyl-magnesium, n-butyl-n-heptylmagnesium,tri-n-hexylaluminum, triisobutylaluminum, triethylaluminum andtrimethylaluminum and mixtures thereof.

If a metal compound of the formula (VII) is used, it is preferablypresent in the catalyst system of the present invention in such anamount that the molar ratio of M² from the formula (VII) to transitionmetal from the transition metal compound of the formula (I) is from800:1 to 1:1, in particular from 200:1 to 2:1.

The catalyst system of the present invention particularly preferablyfurther comprises a support.

To obtain such a supported catalyst system, the unsupported catalystsystem can be reacted with a support. In principle, the order in whichthe support, the transition metal compound and the cocatalyst arecombined is immaterial. The transition metal compound and the cocatalystcan be immobilized independently of one another or simultaneously. Afterthe individual process steps, the solid can be washed with a suitableinert solvent, e.g. an aliphatic or aromatic hydrocarbon.

As supports, preference is given to using finely divided supports whichcan be any organic or inorganic, inert solids. In particular, thesupport can be a porous solid such as talc, a sheet silicate, aninorganic oxide or a finely divided polymer powder (e.g. polyolefin).

Suitable inorganic oxides may be found among oxides of the elements ofgroups 2, 3, 4, 5, 13, 14, 15 and 16 of the Periodic Table of theElements. Examples of oxides preferred as supports include silicondioxide, aluminum oxide and mixed oxides of the elements calcium,aluminum, silicon, magnesium and/or titanium and also correspondingoxide mixtures. Other inorganic oxides which can be used either alone orin combination with the abovementioned preferred oxidic supports are,for example, MgO, ZrO₂, TiO₂ or B₂O₃. An example of a preferred mixedoxide is calcined hydrotalcite.

The support materials used preferably have a specific surface area inthe range from 10 to 1 000 m²/g, a pore volume in the range from 0.1 to5 ml/g and a mean particle size of from 1 to 500 μm. Preference is givento supports having a specific surface area in the range from 50 to 500m²/g, a pore volume in the range from 0.5 to 3.5 ml/g and a meanparticle size in the range from 5 to 350 μm. Particular preference isgiven to supports having a specific surface area in the range from 200to 400 m²/g, a pore volume in the range from 0.8 to 3.0 ml/g and a meanparticle size of from 10 to 100 μm.

The inorganic support can be subjected to a thermal treatment, e.g. toremove adsorbed water. Such a drying treatment is generally carried outat from 80 to 300° C., preferably from 100 to 200° C., with drying atfrom 100 to 200° C. preferably being carried out under reduced pressureand/or under a blanket of inert gas (e.g. nitrogen), or the inorganicsupport can be calcined at from 200 to 1000° C. in order to obtain thedesired structure of the solid and/or the desired OH concentration onthe surface. The support can also be treated chemically using customarydesiccants such as metal alkyls, preferably aluminum alkyls,chlorosilanes or SiCl₄ or else methylaluminoxane. Appropriate treatmentmethods are described, for example, in WO 00/31090. The inorganicsupport material can also be modified chemically. For example, treatmentof silica gel with (NH₄)₂SiF₆ to fluorinate the silica gel surface ortreatment of silica gels with silanes containing nitrogen-, fluorine- orsulfur-containing groups leads to appropriately modified silica gelsurfaces.

Organic support materials such as finely divided polyolefin powders(e.g. polyethylene, polypropylene or polystyrene) can also be used andare preferably likewise freed of adhering moisture, solvent residues orother impurities by means of appropriate purification and dryingoperations before use. It is also possible to use functionalized polymersupports, e.g. supports based on polystyrenes via whose functionalgroups, for example ammonium or hydroxy groups, at least one of thecatalyst components can be immobilized.

In a preferred embodiment of the preparation of the supported catalystsystem of the present invention, at least one transition metal compoundof the formula (I) is brought into contact with at least one cocatalystas activating or cation-forming compound in a suitable solvent, giving asoluble or insoluble, preferably soluble, reaction product, an adduct ora mixture.

The composition obtained in this way is then mixed with the dehydratedor passivated support material, the solvent is removed and the resultingsupported transition metal catalyst system is dried to ensure that allor most of the solvent is removed from the pores of the supportmaterial. The supported catalyst is obtained as a free-flowing powder.Examples of the industrial implementation of the above process aredescribed in WO 96/00243, WO 98/40419 or WO 00/05277.

A further preferred embodiment comprises firstly applying the cocatalystor the cation-forming compound to the support component and subsequentlybringing this supported cocatalyst or cation-forming compound intocontact with the transition metal compound.

Further cocatalyst systems which are of importance therefore likewiseinclude combinations obtained by combining the following components:

-   1st component: at least one defined boron or aluminum compound,-   2nd component: at least one uncharged compound which has at least    one acidic hydrogen atom,-   3rd component: at least one support, preferably an inorganic oxidic    support, and optionally, as 4th component, a base, preferably an    organic nitrogen-containing base, for example an amine, an aniline    derivative or a nitrogen heterocycle.

The boron or aluminum compounds used in the preparation of the supportedcocatalysts are preferably compounds of the formula (VIII)

where

-   R¹⁴ are identical or different and are each hydrogen, halogen,    C₁-C₂₀-alkyl, C₁-C₂₀-haloalkyl, C₁-C₁₀-alkoxy, C₆-C₂₀-aryl,    C₆-C₂₀-haloaryl, C₆-C₂₀-aryloxy, C₇-C₄₀-arylalkyl,    C₇-C₄₀-haloarylalkyl, C₇-C₄₀-alkylaryl, C₇-C₄₀-haloalkylaryl or R¹⁴    is an OSiR¹⁵ ₃ group, where-   R¹⁵ are identical or different and are each hydrogen, halogen,    C₁-C₂₀-alkyl, C₁-C₂₀-haloalkyl, C₁-C₁₀-alkoxy, C₆-C₂₀-aryl,    C₆-C₂₀-haloaryl, C₆-C₂₀-aryloxy, C₇-C₄₀-arylalkyl,    C₇-C₄₀-haloarylalkyl, C₇-C₄₀-alkylaryl, C₇-C₄₀-haloalkylaryl,    preferably hydrogen, C₁-C₈-alkyl or C₇-C₂₀-arylalkyl, and-   M³ is boron or aluminum, preferably boron.

Particularly preferred compounds of the formula (VIII) aretrimethylaluminum, triethylaluminum and triisobutylaluminum.

The uncharged compounds which have at least one acidic hydrogen atom andcan react with compounds of the formula (VIII) are preferably compoundsof the formula (IX), (X) or (XI),

where

-   R¹⁶ are identical or different and are each hydrogen, halogen, a    boron-free C₁-C₄₀ group such as C₁-C₂₀-alkyl, C₁-C₂₀-haloalkyl,    C₁-C₁₀-alkoxy, C₆-C₂₀-aryl, C₆-C₂₀-haloaryl, C₆-C₂₀-aryloxy,    C₇-C₄₀-arylalkyl, C₇-C₄₀-haloarylalkyl, C₇-C₄₀-alkylaryl,    C₇-C₄₀-haloalkylaryl, an Si(R¹⁸)₃ group or a CH(SiR¹⁸ ₃)₂ group,    where-   R¹⁸ is a boron-free C₁-C₄₀ group such as C₁-C₂₀-alkyl,    C₁-C₂₀-haloalkyl, C₁-C₁₀-alkoxy, C₆-C₂₀-aryl, C₆-C₂₀-haloaryl,    C₆-C₂₀-aryloxy, C₇-C₄₀-arylalkyl, C₇-C₄₀-haloarylalkyl,    C₇-C₄₀-alkylaryl, C₇-C₄₀-haloalkylaryl, and-   R¹⁷ is a divalent C₁-C₄₀ group such as C₁-C₂₀-alkylene,    C₁-C₂₀-haloalkylene, C₆-C₂₀-arylene, C₆-C₂₀-haloarylene,    C₇-C₄₀-arylalkylene, C₇-C₄₀-haloarylalkylene, C₇-C₄₀-alkylarylene,    C₇-C₄₀-haloalkylarylene,-   D is an element of group 16 of the Periodic Table of the Elements or    an NR¹⁹ group, where R¹⁹ is hydrogen or a C₁-C₂₀ hydrocarbon radical    such as C₁-C₂₀-alkyl or C₆-C₂₀-aryl, preferably D is oxygen, and-   i is 1 or 2.

Suitable compounds of the formula (IX) include water, alcohols, phenolderivatives, thiophenol derivatives and aniline derivatives, withhalogenated and especially perfluorinated alcohols and phenols being ofparticular importance. Examples of particularly useful compounds arepentafluorophenol, 1,1-bis(pentafluorophenyl)methanol and4-hydroxy-2,2′,3,3′,4′,5,5′,6,6′-nonafluorobiphenyl.

Suitable compounds of the formula (X) include boronic acids and borinicacids, in particular borinic acids having perfluorinated aryl radicals,for example (C₆F₅)₂BOH.

Suitable compounds of the formula (XI) include dihydroxy compounds inwhich the divalent carbon-containing group is preferably halogenated andin particular perfluorinated. An example of such a compound is4,4′-dihydroxy-2,2′,3,3′,5,5′,6,6′-octafluorobiphenyl hydrate.

Examples of combinations of compounds of the formula (VIII) withcompounds of the formula (IX) or (XI) aretrimethylaluminum/pentafluorophenol,trimethylaluminum/1-bis(pentafluorophenyl)methanol,trimethylaluminum/4-hydroxy-2,2′,3,3′,4′,5,5′,6,6′-nonafluorobiphenyl,triethylaluminum/pentafluorophenol ortriisobutylaluminum/pentafluorophenol andtriethylaluminum/4,4′-dihydroxy-2,2′,3,3′,5,5′,6,6′-octafluorobiphenylhydrate, with, for example, reaction products of the following typebeing able to be formed:

Examples of reaction products of the reaction of at least one compoundof the formula (VIII) with at least one compound of the formula (X) are:

The order in which the components are combined is in principleimmaterial.

If desired, the reaction products from the reaction of at least onecompound of the formula (VIII) with at least one compound of the formula(IX), (X) or (XI) and optionally an organic nitrogen base areadditionally combined with an organometallic compound of the formula(III), (IV), (V) and/or (VII) before being combined with the support toform the supported cocatalyst system.

In a preferred variant, the 1st component, e.g. compounds of the formula(VIII), is combined with the 2nd component, e.g. compounds of theformula (IX), (X) or (XI), and a support as 3rd component is combinedwith a base as 4th component and the two mixtures are subsequentlyreacted with one another, preferably in an inert solvent or suspensionmedium. The supported cocatalyst formed can be freed of the inertsolvent or suspension medium before it is reacted with the transitionmetal compound of the formula (I) and, if desired, a metal compound ofthe formula (VII) to form the catalyst system of the present invention.

It is also possible for the catalyst solid of the present inventionfirstly to be prepolymerized with α-olefins, preferably linearC₂-C₁₀-1-alkenes and in particular ethylene or propylene, and theresulting prepolymerized catalyst solid then to be used in the actualpolymerization. The mass ratio of catalyst solid used in theprepolymerization to monomer polymerized onto it is usually in the rangefrom 1:0.1 to 1:200.

Furthermore, a small amount of an olefin, preferably an α-olefin, forexample vinylcyclohexane, styrene or phenyidimethylvinylsilane, asmodifying component, an antistatic or a suitable inert compound such asa wax or oil can be added as additive during or after the preparation ofthe supported catalyst system of the present invention. The molar ratioof additives to transition metal compound is usually from 1:1000 to1000:1, preferably from 1:5 to 20:1.

The novel catalyst systems based on the above-described transition metalcompounds of the formula (I) have the advantage that the transitionmetal compounds used can readily be synthesized with a wide variety ofsubstitution patterns.

The invention further provides, firstly, for the use of a novel catalystsystem as described above for preparing polyolefins and, secondly, aprocess for preparing polyolefins by polymerization or copolymerizationof at least one olefin in the presence of a novel catalyst system asdescribed above.

In general, the catalyst system of the present invention is usedtogether with a further metal compound of the formula (VII), which maybe different from the metal compound or compounds of the formula (VII)used in the preparation of the catalyst system of the present invention,for the polymerization or copolymerization of olefins. The further metalcompound is generally added to the monomer or suspension medium andserves to free the monomer of substances which could impair the catalystactivity. It is also possible for one or more further cocatalytic orcation-forming compounds to be additionally added to the catalyst systemof the present invention in the polymerization process.

The olefins can be functionalized, olefinically unsaturated compoundssuch as ester or amide derivatives of acrylic or methacrylic acid, forexample acrylates, methacrylates or acrylonitrile, or nonpolar olefiniccompounds, including aryl-substituted α-olefins.

Preference is given to polymerizing olefins of the formulaR^(m)—CH═CH—R^(n), where R^(m) and R^(n) are identical or different andare each hydrogen or an organic radical having from 1 to 20 carbonatoms, in particular from 1 to 10 carbon atoms, or R^(m) and R^(n)together with the atoms connecting them can form one or more rings.

Examples of such olefins are 1-olefins having from 2 to 40, preferablyfrom 2 to 10, carbon atoms, e.g. ethylene, propylene, 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene or4-methyl-1-pentene, or unsubstituted or substituted vinyl aromaticcompounds such as styrene and styrene derivatives, or dienes such as1,3-butadiene, 1,4-hexadiene, 1,7-octadiene, 5-ethylidene-2-norbornene,norbornadiene, ethylnorbornadiene or cyclic olefins such as norbornene,tetracyclododecene or methylnorbornene. Preference is given to ethylene,propylene, 1-butene, 1-hexene or 4-methyl-1-pentene.

The catalyst system of the present invention is particularly preferablyused for homopolymerizing ethylene or copolymerizing ethylene withfurther α-olefins, in particular C₃-C₈-α-olefins such as propylene,1-butene, 1-pentene, 1-hexene and/or 1-octene and/or cyclic olefins suchas norbornene and/or dienes having from 4 to 20 carbon atoms, e.g.1,4-hexadiene, norbornadiene, ethylidenenorbomene or ethylnorbornadiene.Very particular preference is given to copolymerizing ethylene withpropylene and/or 1-butene. Examples of such copolymers areethylene-propylene, ethylene-1-butene, ethylene-1-hexene,ethylene-1-octene copolymers, ethylene-propylene-ethylidenenorbornene orethylene-propylene-1,4-hexadiene terpolymers.

The polymerization can be carried out in a known manner in bulk, insuspension, in the gas phase or in a supercritical medium in thecustomary reactors used for the polymerization of olefins. It can becarried out batchwise or preferably continuously, in one or more stages.Solution processes, suspension processes, stirred gas phase processes orgas-phase fluidized-bed processes are all possible. As solvent orsuspension medium, it is possible to use inert hydrocarbons, for exampleisobutane, or else the monomers themselves.

The polymerization can be carried out at from −60 to 300° C. andpressures in the range from 0.5 to 3000 bar. Preference is given totemperatures in the range from 50 to 200° C., in particular from 60 to150° C., very particularly preferably from 70° C. to 120° C., andpressures in the range from 5 to 100 bar, in particular from 15 to 70bar. The mean residence times are usually from 0.5 to 5 hours,preferably from 0.5 to 3 hours. Hydrogen can be used in thepolymerization as molar mass regulator and/or to increase the activity.Furthermore, customary additives such as antistatics can also be used.The catalyst system of the present invention can be used directly forthe polymerization, i.e. it is introduced in pure form into thepolymerization system, or it is admixed with inert components such asparaffins, oils or waxes to improve meterabilty.

The catalyst systems of the present invention are especially useful forpreparing homopolymers and copolymers of ethylene.

The catalysts of the present invention can also be used together withone or more other polymerization catalysts known per se. Thus, forexample, they can be used together with

-   -   Ziegler-Nafta catalysts,    -   supported metallocene catalysts containing transition metals of        groups 4 to 6 of the Periodic Table of the Elements,    -   Catalysts derived from the late transition metals (WO 96/23010),    -   Fe or Co complexes with pyridyidiimine ligands as are disclosed        in WO 98/27124,    -   or chromium oxide catalysts of the Phillips type.

It is possible either to mix various catalysts with one another andmeter them in together or to use cosupported complexes on a commonsupport or else to meter various catalysts separately into thepolymerization vessel at the same point or at different points.

The invention further provides transition metal compounds of the formula(I)

where the variables are as defined above.

The invention further provides for the use of a ligand system of theformula (II)

for preparing a transition metal compound, preferably for preparing atransition metal compound of nickel or palladium, in particular nickel,where the variables are as defined for the formula (I).

Thus, the present invention also provides a process for preparing atransition metal compound, which comprises reacting a ligand system ofthe formula (II) with a transition metal compound. The uncharged diimineligand system is usually reacted with a suitable transition metalcompound, preferably a transition metal halide such as nickel (II)bromide, in a suitable solvent or suspension medium.

The invention further provides a ligand system of the formula (II) inwhich the variables R¹, R^(1′), R² and R^(2′) are as defined for theformula (I) and Y is —N(R³)—N(R⁴)— or —O—N(R⁵)—, where R³, R⁴ and R⁵ areas defined under the formula (I).

The substitution pattern of the diimine ligands of the formula (II) isof critical importance for the polymerization properties of thetransition metal compounds containing these diimine ligands and he sametransition metal ion M.

One possible way of preparing the ligand, namely reacting an imidechloride with a suitable bridging reagent, is known and is described,for example, in J. Org. Chem., Vol. 36, No. 8, 1971, pages 1155-1158.

The invention is illustrated by the following nonlimiting examples.

EXAMPLES

General Preliminary Remarks:

All work was, unless indicated otherwise, carried out in the absence ofair and moisture using standard Schlenk techniques. Apparatus andchemicals were prepared appropriately. The polymer viscosity wasdetermined in accordance with ISO 1628-3.

Preparation of the Ligands

1) Preparation ofN-(2,6-diisopropylphenyl)-N′-[[(2,6-diisopropylphenyl)imino]phenylmethoxy]-N′-methylbenzamidine(1).

a) Preparation of the imide chloride N-(2,6-diisopropylphenyl)benzimidechloride (1a)

1.9 g of N-(2,6-diisopropylphenyl)benzamide (6.7 mmol) were placed in adry Schlenk tube which had been flushed with argon. After addition of 10ml of thionyl chloride, the reaction solution was refluxed for 60minutes. Excess thionyl chloride was taken off under a high vacuum, andthe yellow oil which remained (compound 1a) was dissolved in 20 ml ofmethylene chloride (absolute).b) Preparation ofN-(2,6-diisopropylphenyl)-N′-[[(2,6-diisopropylphenyl)imino]phenylmethoxy]-N′-methylbenzamidine(1)

N-Methylhydroxylamine hydrochloride (0.28 g, 3.35 mmol) was placed in abaked Schienk tube which had been flushed with argon and was dissolvedin absolute ethanol (50 ml). After addition of 10 ml of triethylamine(72 mmol), the resulting suspension was cooled to 40° C. The imidechloride (1a) which had been prepared under a) and dissolved inmethylene chloride was slowly added from a dropping funnel to thesolution b) at −40° C. over a period of 30 minutes. After warming toroom temperature, the reaction mixture (yellow suspension) was stirredfor 1 hour. Subsequent monitoring by means of thin layer chromatography(diethyl ether) indicated complete conversion: a nonpolar componentwhich moved with the solvent front and a polar starting spot wereobtained. The reaction mixture was poured into water (about 100 ml), andthe product was extracted three times with 50 ml each time of ether. Theorganic phase was dried over Na₂SO₄ and the desiccant was filtered off.After the solvent had been taken off on a rotary evaporator, theresulting semicrystalline solid was dissolved in small amounts ofmethylene chloride and filtered through a silica gel bed. The nonpolarcomponent which was very readily soluble in ether was in this waycompletely separated from the polar component. Removal of the solventand recrystallization gave 1.6 g of (1) as a yellow solid.

¹HNMR (CDCl₃): 1.14-1.21 (24H, m, 4×CH(CH ₃)₂), 3.10, 3.42 (4H, sept,4×CH(CH₃)₂), 6.46 (2H, pseudo-d, phenyl), 6.91-7.90 (16H, m, phenyl),¹³C NMR (CDCl₃): 22.0, 23.7, 24.0 (CH(CH₃)₂), 28.9 (CH(CH₃)₂), 39.7(N—CH₃), 122.9, 123.7, 127.1, 127.8, 127.9,128.5, 128.8, 129.0, 129.3,130.4 (C-phenyl), 131.8, 133.1, 142.1, 143.5, 146.4 (C-phenyl,quaternary C), 154.5, 160.4 (C═N), IR (KBr, cm⁻¹): 2970 (m), 2931 (m),2869 (m), 1683 (vs), 1630 (vs), 1602 (m), 1590 (m), 1578 (m), 1492 (m),1459 (m), 1436 (m), 1407 (w), 1383 (m), 1362 (w), 1328 (m), 1287 (w),1264 (m), 1233 (m), 1185 (w), 1108 (m), 1063 (s), 1038 (m), 1030 (m),1013 (vs), 922 (w), 803 (m), 766 (s), 726 (m), MS (FAB): [M+H]⁺=574.4m/e.

2) Preparation ofN-(2,6-dimethylphenyl)-N′-methyl-N′-[(2,6-dimethylphenyl)imino]-phenylmethoxy]benzamidine(2)

a) Preparation of the imide chloride N-(2,6-dimethylphenyl)benzimidechloride (2a)

2.3 g of N-(2,6-dimethylphenyl)benzamide (10.2 mmol) were placed in adry Schienk tube which had been flushed with argon. After addition of 10ml of thionyl chloride, the reaction solution was refluxed for 60minutes. Excess SOCl₂was taken off under a high vacuum, and the yellowoil which remained (compound 2a) was dissolved in 20 ml of methylenechloride (absolute).b) Preparation ofN-(2,6-dimethylphenyl)-N′-methyl-N′-[(2,6-dimethylphenyl)imino]-phenylmethoxy]benzamidine(2)

N-methylhydroxylamine hydrochloride (0.43 g, 5.1 mmol) was placed in abaked Schlenk tube which had been flushed with argon and was dissolvedin absolute ethanol (40 ml). After addition of 10 ml of triethylamine(72 mmol), the resulting suspension was cooled to −40° C. The imidechloride (2a) which had been prepared under a) and dissolved inmethylene chloride was slowly added from a dropping funnel to thesolution b) at −40° C. over a period of 30 minutes. After warming toroom temperature, the reaction mixture (yellow suspension) was stirredfor 1 hour. Subsequent monitoring by means of thin layer chromatography(diethyl ether) indicated complete conversion: a nonpolar component (2)which moved with the solvent front and a polar starting spot(by-product) were observed.

The reaction mixture was poured into water (about 100 ml) and theproduct was extracted three times with 50 ml each time of ether. Afterthe aqueous phase had been neutralized, it was extracted again withether (2×40 ml). The combined organic phases were dried over Na₂SO₄ andthe desiccant was filtered off. After the solvent had been taken off ona rotary evaporator, the resulting semicrystalline solid was dissolvedin small amounts of methylene chloride and filtered through a silica gelbed. The nonpolar component (2) which was very readily soluble in etherwas separated completely from the polar component in this way. Removalof the solvent and crystallization gave 2.2 g of (2) as a yellow solid.

¹H NMR (CDCl₃): 1.95, 2.20 (12H, 2×s, 4×CH₃), 3.61 (3H, s, N—CH₃), 6.52(2H, pseudo-d, phenyl), 6.67-6.96 (7H, m, phenyl), 7.05-7.22 (5H, m,phenyl), 7.41 (2H, pseudo-d, phenyl), ¹³C NMR (CDCl₃): 18.5, 18.8 (CH₃),39.4 (N—CH₃), 122.3, 122.9, 127.0, 127.1, 127.6, 127.8, 127.9, 128.2,128.7, 129.4, 129.5, 130.0, 130.5 (C-phenyl), 131.7, 133.6, 135.5(quaternary C, phenyl), 144.6, 146.1 (C═N—C, quaternary C, phenyl),154.7, 161.5 (C═N, quaternary C), IR (KBr, cm⁻¹): 2919 (w), 1688 (vs),1644 (vs), 1592 (m), 1580 (w), 1493 (w), 1466 (m), 1447 (m), 1405 (w),1326 (s), 1293 (w), 1262 (m), 1246 (m), 1229 (m), 1216 (m), 1183 (w),1104 (w), 1079 (s), 1069 (s), 1027 (m), 1013 (m), 922 (w), 787 (m), 768(vs), 756 (m), 741 (m), 697 (vs), 675 (m), MS: M⁺=461.3 m/e.

3) Preparation ofN-(2,6-diisopropylphenyl)-N′-[[[(2,6-diisopropylphehyl)imino]benzyl]-phenylamino]benzamidine(3).

a) Preparation of the imide chloride N-(2,6-diisopropylphenyl)benzimidechloride (1a) (1a) was prepared from 2,03 g ofN-(2,6-diisopropylphenyl)benzamide (7.2 mmol) and thionyl chloride usinga method analogous to Example 1a).

b) Preparation ofN-(2,6-diisopropylphenyl)-N′-[[[(2,6-diisopropylphenyl)imino]benzyl]-phenylamino]benzamidine(3)

The symmetrically substituted N,N′-diphenylhydrazine (0.70 g, 3.8 mmol)was placed in a baked Schlenk tube which had been flushed with argon andwas suspended in 20 ml of methylene chloride (abs). 1.87 g of Na₂CO₃ (18mmol) were added.

After the reaction solution had been cooled to −70° C., the imidechloride from experiment 3a) dissolved in methylene chloride was slowlyadded from a dropping funnel over a period of 30 minutes. After removingthe cold bath, the mixture was stirred at room temperature for 1 hour.Checking the progress of the reaction by means of TLC (ether/hexane=⅓)showed that the reaction was complete.

The reaction mixture was poured into water (about 100 ml) and theproduct was extracted three times with 50 ml each time of diethyl ether.To improve phase separation, 50 ml of saturated sodium chloride solutionwere added. The combined organic phases were dried over Na₂SO₄ and thedesiccant was filtered off. After the solvent had been taken off on arotary evaporator, the resulting viscous oil was dried in a high vacuumand was subsequently recrystallized from an ethyl acetate/hexane solventmixture. (3) was obtained as a yellow solid in a yield of 0.9 g.

¹H NMR (CDCl₃): 1.00 (12H, d, 2×CH(CH ₃)₂, J=6.6 Hz), 1.25 (12H, d,2×CH(CH ₃)₂, J=6.6 Hz), 3.13 (4H, sept, 4×CH(CH₃)₂), 6.92 (4H, d,phenyl), 7.04 (8H, pseudo-t, phenyl), 7.13-7.36 (14H, m, phenyl), ¹³CNMR (CDCl₃): 21.7, 25.5 (CH(CH₃)₂), 28.9 (H(CH₃)₂), 123.8, 124.5, 124.6,124.9, 127.5, 128.6, 128.8, 129.1, 129.3, 129.5, 129.7(C-phenyl), 132.6(quaternary C, phenyl), 135.3 (N═C—C, quaternary C, phenyl), 137.9 (N—C,quaternary C, phenyl), 145.3 (C═N—C, quaternary C, phenyl), 164.9 (C═N,quaternary C), IR (KBr, cm⁻¹): 2964 (m), 2929 (m), 2869 (m), 1 627 (vs),1607 (s), 1589 (m), 1574 (s), 1497 (m), 1463 (m), 1443 (w), 1356 (w),1328 (m), 1104 (w), 1057 (w), 1007 (w), 822 (w), 805 (w), 789 (w), 778(w), 762 (w), 700 (m), MS (FAB): [M+H]⁺=711.5 m/e.

Synthesis of Complexes

C1 Preparation of N-(2,6-diisopropylphenyl)-N-[[[(2,6-diisopropylphenyl)imino]benzyl]-phenylamino]benzamidinenickel(II)dibromide (C1).

The uncharged di(imino)-[N,N] ligand (3) (0.26 g, 0.37 mmol) was placedin a dry Schienk tube which had been flushed with argon, dissolved in 20ml of methylene chloride (absolute) and, after addition of thedimethoxyethane-stabilized transition metal halide (NiBr₂×2 DME, 0.17 g,0.40 mmol, 1.1 meq), stirred overnight at room temperature (immediatecomplex formation with color change from yellow→green).

The solution was evaporated to dryness in a high vacuum, and 0.3 g of apulverulent, light-green complex (C1) was isolated.

¹H NMR (CD₂Cl₂): 1.07 (12H, d, 2×CH(CH ₃)₂, J=6.9 Hz), 1.31 (12H, d,2×CH(CH ₃)₂, J=6.6 Hz), 3.14 (4H, sept, 4×CH(CH₃)₂), 6.97 (5H, d,phenyl), 7.09 (8H, d, phenyl), 7.18-7.30 (7H, m, phenyl), 7.34-7.39 (6H,m, phenyl), ¹³C NMR (CD₂Cl₂): 21.8, 26.7 (CH(CH₃)₂), 29.5 (CH(CH₃)₂),124.2, 125.1, 125.3, 125.4, 127.5, 127.9, 128.1, 129.1, 129.2, 129.7,129.8 (C-phenyl), 130.2, 133.1, 135.5, 138.4 (quaternary C, phenyl),145.9 (C═N—C, quaternary C, phenyl), 165.5 (C═N).

Polymerization Experiments

Example P1

1.8 mg of the complex (C1) from Example C1, 2 ml of 30% strength byweight MAO solution in toluene (commercially available from Witco) and400 ml of toluene were placed in a 1 l steel auto-clave which had beenmade inert. At 70° C., ethylene was injected to a pressure of 40 bar.This pressure was kept constant during the polymerization time of 90minutes by introduction of further ethylene. The reaction was stopped byventing and the polymer was isolated by filtration, subsequent washingwith methanol and drying under reduced pressure. This gave 1.7 g ofpolymer having a viscosity of 2.5 dl/g.

1. A catalyst system for preparing homopolymers or copolymers ofolefins, which is obtainable by reacting at least one transition metalcompound with at least one cocatalyst which is able to convert thetransition metal compound into a species which displays polymerizationactivity toward at least one olefin, wherein the transition metalcompound has the formula (I),

where M is an element of group 3, 4, 5, 6, 7, 8, 9 or 10 of the PeriodicTable of the Elements or the lanthanides, X are identical or differentand are each an organic or inorganic anionic monovalent ligand, wheretwo radicals X may also be joined to form a divalent radical, n is 1, 2,3 or 4, L¹ is an organic or inorganic uncharged ligand, h is an integerfrom 0 to 4, R¹ and R^(1′) can be identical or different and are eachhydrogen or an organic radical having from 1 to 40 carbon atoms, R²andR^(2′) can be identical or different and are each a substituted orunsubstituted C₆-C₄₀-aryl radical or C₂-C₄₀-heteroaromatic radicalcontaining at least one heteroatom selected from the group consisting ofO, N, S or P, and Y is a divalent group between the two sp²-hybridizedcarbon atoms and is selected from the group consisting of thetwo-membered bridges —N(R³)—N(R⁴)— and —O—N(R⁵)— and the one-memberedbridges —O—, —(R⁶)—, —N(OR⁷)— and —N(NR⁸R⁹)—, where R³, R⁴, R⁵, R⁶, R⁷,R⁸ and R⁹ are identical or different and are each hydrogen or an organicradical having from 1 to 40 carbon atoms, where two adjacent radicalsmay also form a divalent organic group having from 1 to 40 carbon atomswhich together with the atom or atoms connecting its ends forms aheterocyclic ring system.
 2. A catalyst system as claimed in claim 1,wherein the transition metal compound has a formula (I) in which M is Nior Pd, X is halogen, n is 2, h is 0, R¹ and R^(1′) are identical and areeach a substituted or unsubstituted C₆-C₄₀-aryl radical or anitrogen-containing heteroaromatic radical having from 4 to 20 carbonatoms, and the other variables are as defined for the formula (I).
 3. Acatalyst system as claimed in claim 1, wherein the cocatalyst is analuminoxane.
 4. A catalyst system as claimed in claim 1 which furthercomprises a support.
 5. (canceled)
 6. A process for preparingpolyolefins by polymerization or copolymerization of at least one olefinin the presence of a catalyst system as claimed in claim
 1. 7. Atransition metal compound of the formula (I)

where M is an element of group 3, 4, 5, 6, 7, 8, 9 or 10 of the PeriodicTable of the Elements or the lanthanides, X are identical or differentand are each an organic or inorganic anionic monovalent ligand, wheretwo radicals X may also be joined to form a divalent radical, L¹ is anorganic or inorganic uncharged ligand, h is an integer from 0 to 4, R¹and R^(1′) can be identical or different and are each hydrogen or anorganic radical having from 1 to 40 carbon atoms, R² and R^(2′) can beidentical or different and are each a substituted or unsubstitutedC₆-C₄₀-aryl radical or C₂-C₄₀-heteroaromatic radical containing at leastone heteroatom selected from the group consisting of O, N, S or P, and Yis a divalent group between the two sp²-hybridized carbon atoms and isselected from the group consisting of the two-membered bridges—N(R³)—N(R⁴)— and —O—N(R⁵)— and the one-membered bridges —O—, —N(R⁶)—,—N(OR⁷)— and —N(NR⁸R⁹)—, where R³, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ areidentical or different and are each hydrogen or an organic radicalhaving from 1 to 40 carbon atoms, where two adjacent radicals may alsoform a divalent organic group having from 1 to 40 carbon atoms whichtogether with the atom or atoms connecting its ends forms a heterocyclicring system.
 8. (canceled)
 9. (canceled)
 10. (canceled)
 11. A ligandsystem of the formula (II)

for preparing a transition metal compound, where R¹ and R^(1′) can beidentical or different and are each hydrogen or an organic radicalhaving from 1 to 40 carbon atoms, R² and R^(2′) can be identical ordifferent and are each a substituted or unsubstituted C₆-C₄₀-arylradical or C₂-C₄₀-heteroaromatic radical containing at least oneheteroatom selected from the group consisting of O, N, S or P, and Y isa divalent group between the two sp²-hybridized carbon atoms and isselected from the group consisting of the two-membered bridges—N(R³)—N(R⁴)— and —O—N(R⁵)— and the one-membered bridges —O—, —N(R⁶)—,—N(OR⁷)— and —N(NR⁸R⁹)—, where R³, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ areidentical or different and are each hydrogen or an organic radicalhaving from 1 to 40 carbon atoms, where two adjacent radicals may alsoform a divalent organic group having from 1 to 40 carbon atoms whichtogether with the atom or atoms connecting its ends forms a heterocyclicring system.
 12. A ligand system of the formula (II) as claimed in claim11, wherein Y is —N(R³)—N(R⁴)— or —O—N(R⁵)—.
 13. A ligand system of theformula (II) as claimed in claim 12, wherein the variables R¹ and R^(1′)are identical and are each a substituted or unsubstituted C₆-C₄₀-arylradical or a nitrogen-containing heteroaromatic radical having from 4 to20 carbon atoms.
 14. A process for preparing a transition metalcompound, which comprises reacting a ligand system as claimed in claim11 with a transition metal compound.
 15. A catalyst system as claimed inclaim 2, wherein the cocatalyst is an aluminoxane and said catalystsystem further comprises a support.
 16. A process for preparing thecatalyst system of claim 1 comprising reacting at least one transitionmetal compound with at least one cocatalyst which is able to convert thetransition metal compound into a species which displays polymerizationactivity toward at least one olefin, wherein the transition metalcompound has the formula (I).